瑜伽論記 3.262

3.262

四、住者，以無倒文句說此法性，能論文句名為法住，故此法住，以法性為因，故此法性名為法界，界是因義；或以文意及般若等經說彼真如名為法住，所詮從教名為法住，法住體故要有法性方為教依，以體為因以義名界。

Fourth, 'dwelling': explaining this nature of dharmas with non-erroneous words and phrases; the words and phrases that explain are called 'stability of dharmas.' Therefore, this stability of dharmas takes the nature of dharmas as its cause; hence this nature of dharmas is called the 'dharma realm,' where 'realm' (dhātu) has the meaning of 'cause.' Or, based on the meaning of the text and sūtras such as the Prajñā[pāramitā], that tathatā is called 'stability of dharmas'; what is expressed takes its name of 'stability of dharmas' from the teaching. As the entity of the stability of dharmas, there must be the nature of dharmas to serve as the basis of the teaching; taking the entity as cause, it is named 'realm' by its meaning.